DC Offset Cancellation Circuit with Precharged FET Turn-On
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Solution Overview
Problem
Conventional methods for canceling direct current offset current in optical communication systems are slow due to the gradual turn-on speed of field effect transistors, leading to inefficient extraction and stabilization of the offset current, affecting the accuracy and stability of the voltage signal.
Innovation Solution
A direct current offset current cancellation circuit comprising an optical detection module, amplification, filtering, acceleration, charging, and cancellation modules, where the acceleration module provides a target voltage to the charging module, enabling rapid charging and increasing the cancellation voltage, thus accelerating the cancellation process and improving the precision of offset current extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an offset voltage is extracted from a voltage signal and applied to a gate of a field effect transistor to extract direct current offset current, then the direct current offset current can be canceled, but the field effect transistor turns on slowly resulting in slow extraction speed of the direct current offset current
Solution Approach 1:
The patent applies preliminary action by pre-charging a capacitor with a target voltage before the cancellation process begins. When the cancellation is needed, the already-charged capacitor can immediately provide the required voltage to the field effect transistor, eliminating the slow charging phase and enabling rapid turn-on and current extraction.
Solution Approach 2:
The patent extracts the voltage charging function into a separate capacitor component that can be independently controlled and pre-charged. This allows the voltage source to be decoupled from the slow gradual increase mechanism, enabling the field effect transistor to receive the full cancellation voltage immediately when needed.
2Reliability
If the offset voltage is slowly increased from zero to the offset voltage, then the field effect transistor can be turned on, but this results in slow turn-on speed and slow extraction speed of the direct current offset current
Solution Approach 1:
The capacitor is pre-charged to the target voltage in advance, so when the cancellation process is initiated, the full voltage is immediately available to the field effect transistor. This eliminates the time delay associated with gradual voltage increase while maintaining the stability needed for reliable offset current cancellation.
Solution Approach 2:
The patent skips the gradual voltage increase phase by using a pre-charged capacitor that can deliver the full cancellation voltage immediately. This rushes through the time-consuming gradual charging process while still achieving the desired stable cancellation effect.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution quickly and accurately cancels direct current offset current, enhancing the stability and accuracy of the voltage signal output, while also improving the signal-to-noise ratio and reducing baseline drift.
Implementation Method 1
an optical detector converts an optical signal into a current signal
Data Source
AI summary
Embodiments of this application disclose a direct current offset current cancellation circuit and method, and a related device. An optical detection module included in the cancellation circuit in this application is configured to output a current signal. A first amplification module is configured to convert and amplify the current signal into a voltage signal. A first filtering module is configured to filter the voltage signal to obtain a direct current offset voltage. An acceleration module is configured to provide a target voltage for a charging module. The charging module is configured to output a cancellation voltage based on the target voltage and the direct current offset voltage. A direct current cancellation module is configured to cancel a direct current offset current in the current signal based on the cancellation voltage.